A new optical technology will mean better artificial lenses for the human eye; a closer resemblance to the eye's natural lens will remove distortions which were previously unavoidable

Artificial eye lenses have never been a perfect replacement for the natural ones we're born with. One reason for this is that artificial lenses have a single refractive index, while the natural lens has a range of different indices. The refractive index is the property in a material which determines the way light travels through it; specifically how the angle of incoming light changes as it passes from one material to another. The natural lens has several different refractive indices, and the human eye is optimized for this. Artificial lenses with one refractive index, such as those used in cataracts surgery, thus often cause visual distortions.

Diagram over how light is refracted through a natural lens

Case Western University, the Rose-Hulman Institute of Technology, the U.S. Naval Research Laboratory, and a company called PolymerPlus have been working on creating a new lens capable of having several refractive indices, and thus being able to serve as a more perfect replacement for the human one. The technology they've created is called GRIN, or Gradient Refractive Index Optics.

The group has used GRIN to create a new lens, which is composed of layers upon layers of nano-scale polymer films. Each layer has slightly different optical properties, and when combined on top of each other, the result is a lens through which light is incrementally bent at different angles depending on where it strikes the lens. Michael Ponting, president of PolymerPlus, explains: “It’s a very efficient means of controlling the pathway of light without relying on complicated optics,"

A GRIN lens

The most obvious application for the technology is medical, but in the future the technology could be more widespread. As Ponting stated, the technology allows for very efficient means of controlling light; meaning it could one day have consumer or military applications in optical systems by reducing the number of components needed.